Steering wheels for vehicles comprise a base structure including a circular part, or rim, that is connected to a hub by spokes. This base structure is either made of solid material or it may comprise a core or frame of metal or other suitable material (plastic, carbon fiber and the like) covered by an expanded material. The “skin” of the steering wheel, in particular of the circular rim, may be integral with the material of the base structure or include a decorative cover, or veneer, of valuable material, for example, briar or other valuable wood. This solution is particularly expensive and is used in luxury car models.
U.S. Pat. No. 6,282,982 teaches a production process for steering wheels wherein two half shells including several layers of wood and thermosetting materials are thermoformed and then assembled and bound around the base structure. The steering wheel thus assembled is treated in a known way, for example, with lacquer or enamel, to obtain the final product.
This process and the similar, known processes in the art have the drawbacks of being time-consuming and of requiring a relatively high amount of material for the production of the assembled steering wheel. In particular, it takes approximately four minutes to produce the half shells by hot mold thermosetting and the assembly and gluing times of the half shells onto the base structure is approximately five to ten minutes.
A further problem of the known art is that the mold used has to be kept at high temperatures in order to effect the cross-linking of the thermosetting polymers. Another problem with the previous art is that fabrics cannot be used as an external covering or veneer.